Appendix 1 - Risk Assessment

Transcription

1 Appendix 1 - Risk Assessment Supporting information for APP202788: New risk assessment for a substance (Para-Ken 250) containing 250 g/l of paraquat Note: this document is an appendix to the application for grounds for reassessment of the approvals for paraquat and all substances containing paraquat or its salts.

2 2 1. Overview 1.1. This risk assessment was completed as part of the evaluation for application APP202697, Para-Ken 250. Para-Ken 250 contains a similar amount of paraquat to other approved substances containing paraquat and is applied at similar rates, therefore, it is expected to have similar risks to other paraquat-containing substances and the findings of this risk assessment are considered applicable to all other paraquat-containing products Paraquat-containing products are used in agriculture, forestry and for general weed control in industrial and urban areas; these uses are described in detail in section Products containing paraquat are approved Australia, Canada and the USA, but paraquat is banned in the EU. Its use is currently under review in Australia and the USA. Summary of findings from the risk assessment 1.4. Predicted exposures of operators during mixing, loading and application of Para-Ken 250 are greater than the acceptable operator exposure limit (AOEL) for paraquat, even with the use of full personal protective equipment (PPE) including the use of a respirator. This indicates that users may not be able to achieve an acceptable level of personal protection Paraquat products are not available to the general public because these substances are classed as 6.1A (very acutely toxic to humans) and are therefore restricted to use by approved handlers. However, paraquat may be used by councils, or their contractors, to spray road edges and public areas. The predicted exposures for children playing directly on a treated area (such as children playing on street verges) are substantially higher than the AOEL Paraquat products pose a high risk to aquatic organisms (algae) and birds when applied as a broadcast spray. The recommended buffer zone required to reduce the effects of Para-Ken 250 to an acceptable level was greater than 254 m. We consider that this size buffer zone is so large that it is likely to prevent this substance being used as intended.

3 3 Table of contents 1. Overview Use pattern Human health risk assessment... 8 Quantitative worker (operator) risk assessment... 8 Summary and conclusions of the human health risk assessment Environmental risk assessment Robust study summaries and input data Risk assessment methodology Consideration of threatened native species Aquatic risk assessment Terrestrial risk assessment Earthworm risk assessment Non-target plant risk assessment Bird risk assessment Bee risk assessment Non-target arthropod risk assessment Summary and conclusions of the ecological risk assessment References List of Tables Table 1 GAP table (From application APP202697)... 6 Table 2 Model inputs using an existing AOEL for paraquat... 8 Table 3 Other inputs for human worker (operator) and re-entry exposure modelling... 8 Table 4 Output of human worker (operator) mixing, loading and application exposure modelling10 Table 5 Output of human bystander exposure modelling Table 6 Output of recreational exposure modelling Table 7 Summary of environmental fate data on paraquat dichloride Table 8 Summary of ecotoxicological data on paraquat dichloride Table 9 Levels of concern as adopted by EPA New Zealand Table 10 Input parameters for GENEEC2 analysis Table 11 risk quotients derived from the GENEEC2 model and toxicity data Table 12 Chronic risk quotients derived from the GENEEC2 model and toxicity data Table 13 Assessment factors for derivation of PNECsed Table 14 Levels of concern as adopted by the EPA... 28

4 4 Table 15 in-field TER value for earthworms Table 16 off-field TER value for earthworms Table 17 Basic drift values for two applications Table 18 Basic drift values for four applications Table 19 TER value for non-target plant seedling emergence Table 20 TER value for non-target plant vegetative vigour Table 21 TER value for non-target plant Table 22 Exposure of birds for acute and reproduction screening assessment Table 23 Measures of exposure and toxicity used in the reproduction assessment Table 24 TER values for acute dietary and reproductive risk assessment (screening) Table 25 TER values for acute dietary and reproductive risk assessment (tier 1) Table 26 Calculation of EEC values Table 27 RQ values for acute oral and contact exposure to bees... 46

5 5 2. Use pattern 2.1. Paraquat is a non-selective herbicide which is used by commercial users in the agricultural sector and for general weed control around buildings, drains and waterways. It can only be purchased and applied by a person holding a relevant Approved Handler s Certificate. Products containing paraquat are not available to the general public through supermarkets and hardware stores Paraquat-containing products are diluted with water and applied using aerial application, boom sprayers or backpack sprayer. However, Para-Ken 250 was not intended to be applied aerially, so this has not been included in the risk assessment Table 1 shows the GAP (Good Agricultural Practise) table used to produce the risk assessment for Para-Ken 250.

6 6 Table 1 GAP table (From application APP202697) Crop and/or situation (a) Prod uct code F G or I (b) Pests or Group of pests controlled (c) Formulation Application Application rate per treatment PHI (days) (l) Rem arks : (m) Type (d-f) Conc. of as (i) method kind (f-h) growth stage & season (j) No min max (k) interval between application s (min) kg as/hl min max water L/ha min max kg as/ha min max Clover seeds Fence lines, Stock yards, Street verges, Streets and Industrial sites Forestry Lucerne F F F F Grasses, Broad Leaf Weeds Grasses, Broad Leaf Weeds Grasses, Broad Leaf Weeds Grasses, Annual Broad Leaf Weeds SL SL SL SL 250 g/l 250 g/l 250 g/l 250 g/l High volume broadcast High volume broadcast, Handgun, Knapsack High volume broadcast High volume broadcast 2 weeks before closing clover crop for seed. All stages and growth seasons but more predominately in the spring/summer/ autumn period All stages in spring/summer/ autumn season Winter while Lucerne is dormant days days days days Non selective weed control F Barley grasses Australia sedges Tall rescue and rushes SL 250 g/l Handgun During the active growth phase of the target species but before seed maturity. Predominately in the spring/summer/ autumn period days

7 7 Remarks (a) For crops, the EU and Codex classifications (both) should be used; where relevant, the use situation should be described (e.g. fumigation of a structure) (b) Outdoor or field use (F), glasshouse application (G) or indoor application (I) (c) e.g. biting and sucking insects, soil borne insects, foliar fungi, weeds (d) e.g. wettable powder (WP), emulsifiable concentrate (EC), granule (GR) (e) GCPF Codes - GIFAP Technical Monograph No 2, 1989 (f) All abbreviations used must be explained (g) Method, e.g. high volume spraying, low volume spraying, spreading, dusting, drench (h) Kind, e.g. overall, broadcast, aerial spraying, row, individual plant, between the plants - type of equipment used must be indicated (i) g/kg or g/l (j) Growth stage at last treatment (BBCH Monograph, Growth Stages of Plants, 1997, Blackwell, ISBN ), including where relevant, information on season at time of application (k) The minimum and maximum number of application possible under practical conditions of use must be provided (l) PHI - minimum pre-harvest interval (m) Remarks may include: Extent of use/economic importance/restrictions

8 8 3. Human health risk assessment 3.1. Para-Ken 250 contains paraquat dichloride, a salt of paraquat, the application rates posed by the applicant are higher than the application rates of other approved substances containing this active ingredient. Therefore, a quantitative human health risk assessment was undertaken The risk was calculated as a risk quotient (RQ) with is the calculated level of exposure divided by an exposure level, such as the acceptable operator exposure level (AOEL). Quantitative worker (operator) risk assessment Critical endpoint definition 3.3. The Tables 2 and 3 show the endpoints and input values used in the models that were used to estimate the risks to human health. Table 2 Model inputs using an existing AOEL for paraquat Available international AOELs Key systemic effect NOAEL (mg/kg bw/day) Uncertainty factors AOEL (mg/kg bw/day) Modifications Remarks EU (2003) Pulmonary lesions, clinical chemistry, and urine analysis (90 day and 1 year dog studies) AOEL short term: AOEL long term: None Corrected for 10% oral absorption *NOAEL is the no observable adverse effect level, which is determined experimentally Table 3 Other inputs for human worker (operator) and re-entry exposure modelling 1 Active Physical form Concentration of active (g/l) Maximum application rate (g a.i./ha) Dermal absorption (%) Concentrate Spray AOEL (mg/kg bw/day) Paraquat ion Liquid Comments on inputs for human worker (operator) exposure modelling input parameters: Dermal absorption 3.4. The applicant did not provide dermal absorption data for paraquat in the formulation Para-Ken 250. Therefore, we used default values for dermal absorption, as recommended in the EFSA (European Food Safety Authority) Guidance on Dermal Absorption ( ) and OECD 1 The EPA s operator exposure assessment is based on a modification of the approach used by European regulators. Full details of the methodology can be provided on request. 2 EFSA 2012 Guidance on dermal absorption. EFSA Panel on Plant Protection Products and their Residues. EFSA Journal 2012: 10(4):2665

9 9 Guidance Notes on Dermal Absorption ( ). For pesticides, we have agreed to adopt less conservative default values than those proposed in the EFSA and OECD guidance, using default values proposed by Aggarwal et al. ( ), which are based on a review of a robust data set of 295 in vitro human dermal absorption studies with over 150 agrochemical active ingredients. These default values are 2% for solid concentrates, 6% for liquid concentrates and 30% for spray dilutions We note that the oral absorption of paraquat is low (10%). We considered whether it may be possible to use this information to refine the dermal absorption values, however, no oral absorption, distribution, metabolism and excretion (ADME) studies are available with the Para- Ken 250 formulation and the influence of the co-formulants in this formulation on dermal absorption is unknown. Therefore, we do not consider it appropriate to use oral absorption as a surrogate dermal absorption value We also note that assessments of the EU and the US EPA have noted that dermal absorption of paraquat may be as low as 0.5%. However, these conclusions predate the introduction of the OECD and EFSA guidance on dermal absorption which provides criteria for deciding when it is appropriate to read across data to a specific formulation. In this case, information is not available as to the formulations or vehicles used to perform the dermal absorption studies with paraquat and how these compare to the Para-Ken 250 formulation In the absence of more information, we consider it is appropriate to use the default dermal absorption values in the present assessment, although it is acknowledged that these values may result in an overestimate of exposure. Work rates 3.8. Para-Ken 250 is intended to be used to control weeds in Lucerne, clover seed crops, forestry, industrial sites, streets and for barley grass control by high volume broadcast and by handgun application. The default work rate for boom spraying for cereals, legume vegetables, bare soil and grasslands in our exposure assessment model is 50 ha per day. We have assumed that this work rate is appropriate for the proposed uses of Para-Ken The default work rate for knapsack/handgun spraying is 1 ha per day. df Accessed 05/02/ OECD 2011 OECD Guidance notes on dermal absorption. Series on Testing and Assessment, No ENV/JM/MONO(2011)36 Accessed 05/02/ Aggarwal et al Assessment of an extended dataset of in vitro human dermal absorption studies on pesticides to determine default values, opportunities for read-across and influence of dilution on absorption. Regul Toxicol Pharmacol 72:

10 10 Table 4 Output of human worker (operator) mixing, loading and application exposure modelling Exposure Scenario Boom Estimated operator exposure (mg/kg bw/day) No PPE 5 during mixing, loading and application Gloves only during mixing and loading Gloves only during application RQ Full PPE during mixing, loading and application (excluding respirator) Full PPE during mixing, loading and application (including FP1, P1 and similar respirator achieving 75 % inhalation exposure reduction) Full PPE during mixing, loading and application (including FP2, P2 and similar respirator achieving 90 % inhalation exposure reduction) Backpack - High-Level Target No PPE during mixing, loading and application Gloves only during mixing and loading Gloves only during application Full PPE during mixing, loading and application (excluding respirator) Full PPE during mixing, loading and application (including FP1, P1 and similar respirator achieving 75 % inhalation exposure reduction) Full PPE during mixing, loading and application (including FP2, P2 and similar respirator achieving 90 % inhalation exposure reduction) Outcomes of the worker (operator) exposure assessment Predicted exposures of workers (operators) during mixing, loading and application of Para-Ken 250 were greater than the AOEL for paraquat for both boom and knapsack spraying, even with the use of full PPE including a respirator 6. 5 Full PPE includes: gloves, hood/visor, coveralls, and heavy boots during application. The model only provides for use of gloves at mixing loading. 6 Gloves, hood/visor, coveralls, and heavy boots with a respirator

11 11 Re-entry exposure assessment Para-Ken 250 is intended to be used primarily before sowing or transplanting, or before crop emergence. Therefore, we anticipate that re-entry worker exposure to Para-Ken 250 is likely to be minimal and no quantitative re-entry worker exposure assessment is required. Quantitative bystander risk assessment The AOEL derived for operator and re-entry worker assessment in Table 2 also used for the bystander assessment calculations We consider that the main potential source of exposure to the general public for substances of this type (other than via food residues which will be considered as part of the registration of this substance under the Agricultural Compounds and Veterinary Medicines (ACVM) Act 1997) is via spray drift. In terms of bystander exposure, toddlers are regarded as the most sensitive subpopulation and are regarded as having the greatest exposures. For these reasons, the risk of bystander exposure is assessed in this sub-population. We have agreed that the AOEL used for operator and re-entry worker exposure assessment should be used for the bystander assessment because the use of an oral chronic reference dose (CRfD) is likely to be over precautionary The bystander exposure in Table 5 is calculated based on the exposed person being a 15 kg toddler exposed through contact with surfaces 8 m from the edge of the application area. The corresponding buffer zone is the distance that the toddler is required to be from the edge of the application area to ensure that their level of exposure is at the AOEL level. Table 6 shows the equivalent value for the same toddler who is 0 m from the edge of the application area, this is to represent exposure to people who are in the application area, for instance if paraquat was used to treat weeds in a park or public area. Table 5 Output of human bystander exposure modelling Exposure Scenario Boom Estimated exposure (µg/kg bw/day) RQ Buffer zone High boom, fine droplets High boom, coarse droplets Low boom, fine droplets Low boom, coarse droplets The EPA s bystander exposure assessment is based on a modification of the approaches used by European regulators and the US EPA. Spray drift deposition from ground-based application is estimated using the AGDISP model. Spray drift deposition from aerial application is estimated using the AGDISP model along with appropriate New Zealand input parameters We note that the intended use pattern for Para-Ken 250 includes street verges. It is possible that in some cases children may play in such areas. Therefore, we have also assessed the potential recreational exposure for children. This assesment uses the same approach as the

12 12 bystander exposure assessment; apart from the fact that the area of contact is 0 m from the application area. Table 6 Output of recreational exposure modelling Estimated exposure 0 m from an application area (µg/kg bw/day) RQ Outcomes of the bystander exposure assessment The predicted exposures of bystanders are greater than the AOEL for paraquat. The level of exposure could be reduced if spraying of Para-Ken 250 were limited to use of coarse droplets, a minimum buffer zone of 16 or 30 m from sensitive areas were applied for low boom and high boom applications, respectively Exposures for children playing directly on a treated area are also higher than the AOEL. Summary and conclusions of the human health risk assessment Predicted exposures of operators during mixing, loading and application of Para-Ken 250 are greater than the AOEL for paraquat, even with the use of full PPE including a respirator Given the use pattern re-entry worker exposure to Para-Ken 250 is likely to be minimal and therefore no quantitative re-entry worker exposure assessment has been performed Predicted exposures of a bystander 8 m away from the edge of an application area are greater than the acceptable level for paraquat. The level of exposure could be reduced if spraying of Para-Ken 250 were limited to the use of coarse droplets, a minimum buffer zone of 16 or 30 m from sensitive areas were applied for low boom and high boom applications, respectively Predicted exposures for children playing directly on a treated area are also substantially higher than the AOEL The risk assessment includes some default assumptions which leads to conservatism in the risk assessment. Information that could potentially be used to refine the risk assessment includes: Dermal absorption data for the active ingredients in the Para-Ken 250 formulation Information on the expected work rates per day for each use scenario Operator exposure studies Confirmation that the application rate relates to the paraquat ion Information on the relevance of the recreational exposure scenario included in the present risk assessment However, we note that even if the low dermal absorption value of 0.5 %, which was proposed by the EU in 2002, were used in this risk assessment, the predicted exposures would still be greater than the AOEL for operators mixing, loading and applying Para-Ken 250 by boom and knapsack application methods (RQs of 4 and 6, respectively).

13 13 4. Environmental risk assessment Robust study summaries and input data For the formulation 4.1. The applicant for Para-Ken 250 provided ecotox studies performed with a formulation coded PARAQUAT 20% SL, containing 200 g/l paraquat dichloride. The amount of paraquat dichloride in PARAQUAT 20% SL is less than the amount of paraquat dichloride in Para-Ken 250, which contains 250 g paraquat dichloride/l. The applicant provided a bridging statement where reasons are presented to read-across the data from PARAQUAT 20% SL to the Para- Ken 250. The applicant claims that since the difference in the amount of paraquat dichloride between the two formulations is 50 g/l the results may be used in the risk assessment. We summarised the studies provided by the applicant and used the results when deemed appropriate for the risk assessment. With the active ingredient 4.2. The information on the environmental fate and behaviour and ecotoxicological data of paraquat dichloride are depicted in Table 7 and Table 8. Table 7 Summary of environmental fate data on paraquat dichloride Test Paraquat dichloride Hydrolysis Rapid biodegradation in water Aqueous photolysis Aerobic degradation in water (water/sediment) Hydrolytically stable at ph 5, 7 and 9 after 30 days at 25 and 40 C. Not rapidly biodegradable. Photolytically stable at environmentally relevant wavelengths. - Anaerobic degradation - Bioaccumulation Aerobic degradation in soil (laboratory) Aerobic degradation in soil (field) The log Kow for paraquat dichloride is -4.5 at 20 C indicating that bioaccumulation is unlikely. Paraquat is expected to be almost immobile in soil. The estimated average field half-life of paraquat in soil is 1000 days. No half-life calculated, estimates indicate more than 10 years. Soil photolysis - Adsorption/desorption (Koc values) Koc = Volatilisation Not relevant, due to low vapour pressure. - No data provided

14 14 Table 8 Summary of ecotoxicological data on paraquat dichloride Test Paraquat dichloride Reference Paraquat 20% SL / fish LC50 = mg/l (Barbus sharpeyi) EPA internal database LC50 = mg/l, equivalent to mg a.i./l) / aquatic invertebrates EC50 = 1.2 mg/l (Daphnia magna) EPA internal database EC50 = mg/l, equivalent to 3.49 mg a.i./l Algae EC50 = 0.32 mg/l (Selenastrum capricornutum) EPA internal database ErC50 = 2.41 mg/l, equivalent to 0.48 mg a.i/l (Pseudokirchneriella subcapitata) Algae - diatom EC50 = mg/l (Naviculla peliculosa) EPA internal database - Aquatic plant (Lemna gibba) EC50 = mg/l EPA internal database - Chronic / fish Chronic / Aquatic invertebrates Chronic toxicity sediment dwelling organism - Chironomus NOEC = 0.12 mg/l (Daphnia magna) NOEC = 100 mg/kg (sediment); NOEC = mg/l (water phase only) SANCO, SANCO, / Earthworm LC50 > 1380 mg/kg soil EPA internal database LC50 > 210 mg a.i./kg soil Chronic / Earthworm Soil microorganisms No adverse effects were observed after application up to 720 kg a.i/ha in one year. SANCO, 2003 No adverse effects on carbon and nitrogen transformations after application up to 3 kg a.i./ha. EC25 = 0.95 kg/ha (seedling emergence, cocklebur) Non target plants EC25 = kg/ha (vegetative vigour, cocklebur) EPA internal database - NOEC = kg/ha (vegetative vigour, cocklebur) / bird LC50 = 35 mg/kg bw LC50 = 176 mg/kg bw SANCO, 2003 EPA internal database LC50 = mg/kg bw, equivalent to mg a.i./kg bw Reproduction bird NOEC = 2.8 mg/kg bw/d USEPA, 1997 SANCO,

15 15 Test Paraquat dichloride Reference Paraquat 20% SL / bees LC50 (contact) = 9.26 µg/bee LC50 (oral) = 9.06 µg/bee (120-hr EPA internal database LC50 (contact) = µg/bee (equivalent to 8.25 µg a.i./bee) study) SANCO, 2003 Non-target arthropods No data provided - NOEC No observed effect concentration - LD 50 and LC 50 are the median lethal dose or concentration (respectively) of a toxin at which 50% of the test population die. - EC 50 and EC 25 are the environmental concentrations at which 50% and 25% of the population die when exposed to the toxin. Risk assessment methodology 4.3. Methods used to assess environmental exposure and risk differ between environmental compartments (Table 9). Table 9 Reference documents for environmental exposure and risk assessments Aquatic organisms Sediment organisms Soil organisms, invertebrates (macroinvertebrates) Environmental exposure (GEN)eric (E)stimated (E)nvironmental (C)oncentration Model Version August 2002 AgDRIFT and EPA Software (see notes below) Guidance on information requirements and chemical safety assessment, Chapter R.16: Environmental Exposure Estimation, Version: 2 - May 2010 Soil persistence models and EU registration. The final report of the work of the Soil Modelling Work Group of FOCUS (Forum for the Co-ordination of pesticide fate models and their use) 29 February 1997 Risk assessment Overview of the Ecological Risk Assessment Process in the Office of Pesticide Programs, U.S. Environmental Protection Agency. Endangered and threatened Species Effects Determinations 23 January 2004 Guidance on information requirements and chemical safety assessment, Chapter R.10: Characterisation of dose [concentration]-response for environment May 2008 SANCO/10329/2002 rev 2 final. Guidance Document on terrestrial ecotoxicology under Council Directive 91/414/EEC- 17 October 2002 Bees Terrestrial organisms, invertebrates (non-target arthropods) Terrestrial vertebrates (birds) Guidance for assessing pesticide risks to bees. US EPA, Health Canada Pest Management Regulatory Agency, California Department of Pesticide Regulation, 19 June 2014 Guidance document on regulatory testing and risk assessment procedures for plant protection products with non-target arthropods. From ESCORT 2 Workshop 21/23 March 2000 Guidance of EFSA. Risk assessment to birds and mammals 17 December EFSA calculator tool

16 16 Environmental exposure Risk assessment SANCO/4145/2000 final. Guidance Document on risk assessment for birds and mammals under Council Directive 91/414/EEC- 25 September 2002 Secondary poisoning and biomagnification Technical Guidance Document on risk assessment in support of Commission Directive 93/67/EEC on Risk Assessment for new notified substances, Commission Regulation (EC) No 1488/94 on Risk Assessment for existing substances, Directive 98/8/EC of the European Parliament and of the Council concerning the placing of biocidal products on the market Part II Guidance of EFSA. Risk assessment to birds and mammals 17 December 2009 EFSA calculator tool SANCO/4145/2000 final. Guidance Document on risk assessment for birds and mammals under Council Directive 91/414/EEC- 25 September We used two different models for assessing the EEC and associated risks: 4.5. Generic Estimated Environmental Concentration Model v2 (GENEEC2) surface water exposure model (USEPA, 2001) estimates the concentration of substance in surface water which may arise as a result of surface runoff and spray drift We used the AgDRIFT model to examine how buffer zones would reduce the amount of paraquat that entered neighbouring receiving waters. The AgDRIFT model was developed under a cooperative Research and Development Agreement, CRADA, between the EPA, USDA, US Forest Service, and SDTF. AgDRIFT incorporates a proposed overall method for evaluating off-site deposition of aerial, orchard or ground applied pesticides, and acts as a tool for evaluating the potential of buffer zones to protect sensitive aquatic and terrestrial habitats from undesired exposures. Calculations are made assuming the receiving water is a 30 cm deep pond. The model is used to estimate the buffer zone distance that would be needed to reduce the calculated concentration of the substance in the water that is present due to spray drift), to the level needed to give an acute risk quotient of 0.1 or less. It is noted that unlike GENEEC2, AgDRIFT only considers transport by spray drift, input through run-off, volatilisation, etc. will pose additional risks. Consideration of threatened native species 4.7. No studies are requested to be conducted on native New Zealand species; the risk assessment is based on studies performed on standard surrogate species from Europe or North America. Uncertainty factors included in the risk assessment process encompass the possible susceptibility variations between the surrogate species and the native New Zealand species. However, these factors are designed to protect populations not individual organisms. We acknowledge that these factors may not be protective enough for for which the survival of the population could depend on the survival of each and every individual Therefore, the US EPA approach for risk assessment of endangered species has been implemented. Additional uncertainty factors are included, depending on the type of organisms. US EPA consider higher factors when organisms cannot escape the contaminated area (for aquatic organisms for instance) than for birds.

17 US EPA has not defined any additional factor for soil organisms except for plants, so we applied the same approach as for aquatic organisms, because soil invertebrates won t be able to escape from the contaminated area For the purpose of this risk assessment, the are those included in the following categories of the New Zealand Threat Classification System: threatened (nationally critical, nationally endangered, nationally vulnerable) and at risk (declining, recovering, relict, and naturally uncommon). Aquatic risk assessment For Class 9 substances, irrespective of the intrinsic hazard classification, the ecological risk can be assessed for a substance by calculating a RQ value based on an estimated exposure concentration. Such calculations incorporate toxicity values, exposure scenarios (including spray drift, leaching and run-off, application rates and frequencies), and the half-lives of the component(s) in water. For the aquatic environment, the calculations provide an estimated environmental concentration (EEC) which, when divided by the L(E)C50 or a NOEC, gives a RQ acute or chronic. RQ = EEC short term L(E)C 50 Chronic RQ = EEC long term NOEC If the RQ exceeds a predefined level of concern, this suggests that it may be appropriate to refine the assessment or apply controls to minimise off-site movement of the substance. Conversely, if a worst-case scenario is used, and the level of concern is not exceeded, then we presume that the risk is low and is able to be managed by the prescribed controls We used the levels of concern (LOC) developed by the USEPA (Urban and Cook, 1986) to determine whether a substance poses an environmental risk (Table 9). Table 9 Levels of concern as adopted by EPA New Zealand Endpoint LOC Presumption Aquatic (fish, invertebrates, algae, aquatic plants) RQ 0.5 High acute risk RQ Risk can be mitigated through restricted use RQ < 0.1 Low risk Chronic RQ 1 High chronic risk Aquatic RQ 0.05 High acute risk Chronic RQ 0.1 High chronic risk

18 18 Endpoint LOC Presumption Plants (terrestrial) RQ /TER RQ 1 calculated on the basis of EC25 or TER < 5 calculated on the basis of EC50 High acute risk Threatened plants species (terrestrial) RQ 1 calculated on the basis of the NOEC or EC05 High acute risk GENEEC2 modelling Calculation of expected environmental concentrations The parameters used in GENEEC2 modelling are listed in Table 10. Table 10 Input parameters for GENEEC2 analysis Clover seed crops Non-crop situations: fence lines, streets, industrial sites Forestry Lucerne Non selective weed control (barley grass) Application rate (g a.i./ha) Application frequency Application interval (days) 28 days Koc (Lowest value of a non-and soil) Aerobic soil DT50 (days) 1000 Pesticide wetted in? No Methods of application High Vol broadcast HV broadcast, knapsack, handgun HV broadcast HV broadcast Handgun No spray zone No Water solubility (ppm) Hydrolysis (DT50 in days) Stable Aerobic aquatic DT50 whole system (days)** 2000 Aqueous photolysis DT50 (days) Stable Highest concentration Peak EEC (mg/l) Low dose =

19 19 Clover seed crops Non-crop situations: fence lines, streets, industrial sites Forestry Lucerne Non selective weed control (barley grass) High dose = ** Twice the value of the DT 50 soil according to the GENEEC2 recommendations Output from the GENEEC2 model for paraquat dichloride RUN No. 1 FOR Paraquat dichlor ON Clover * INPUT VALUES * RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE NO-SPRAY INCORP ONE(MULT) INTERVAL Koc (PPM ) (%DRIFT) (FT) (IN) 0.356( 0.705) ******* GRHIFI( 6.6) FIELD AND STANDARD POND HALFLIFE VALUES (DAYS) METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED (FIELD) RAIN/RUNOFF (POND) (POND-EFF) (POND) (POND) ****** GENERIC EECs (IN MICROGRAMS/LITER (PPB)) Version 2.0 Aug 1, 2001 PEAK MAX 4 DAY MAX 21 DAY MAX 60 DAY MAX 90 DAY GEEC AVG GEEC AVG GEEC AVG GEEC AVG GEEC RUN No. 2 FOR Paraquat dichlor ON Non crop s * INPUT VALUES * RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE NO-SPRAY INCORP ONE(MULT) INTERVAL Koc (PPM ) (%DRIFT) (FT) (IN) 1.335( 5.190) ******* GRHIFI( 6.6) FIELD AND STANDARD POND HALFLIFE VALUES (DAYS) METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED (FIELD) RAIN/RUNOFF (POND) (POND-EFF) (POND) (POND) N/A ****** GENERIC EECs (IN MICROGRAMS/LITER (PPB)) Version 2.0 Aug 1, 2001 PEAK MAX 4 DAY MAX 21 DAY MAX 60 DAY MAX 90 DAY GEEC AVG GEEC AVG GEEC AVG GEEC AVG GEEC RUN No. 3 FOR Paraquat dichlor ON Forestry * INPUT VALUES * RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE NO-SPRAY INCORP ONE(MULT) INTERVAL Koc (PPM ) (%DRIFT) (FT) (IN)

20 ( 1.764) ******* GRHIFI( 6.6) FIELD AND STANDARD POND HALFLIFE VALUES (DAYS) METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED (FIELD) RAIN/RUNOFF (POND) (POND-EFF) (POND) (POND) N/A ****** GENERIC EECs (IN MICROGRAMS/LITER (PPB)) Version 2.0 Aug 1, 2001 PEAK MAX 4 DAY MAX 21 DAY MAX 60 DAY MAX 90 DAY GEEC AVG GEEC AVG GEEC AVG GEEC AVG GEEC RUN No. 4 FOR Paraquat dichlor ON Lucerne * INPUT VALUES * RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE NO-SPRAY INCORP ONE(MULT) INTERVAL Koc (PPM ) (%DRIFT) (FT) (IN) 0.534( 1.058) ******* GRHIFI( 6.6) FIELD AND STANDARD POND HALFLIFE VALUES (DAYS) METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED (FIELD) RAIN/RUNOFF (POND) (POND-EFF) (POND) (POND) N/A ****** GENERIC EECs (IN MICROGRAMS/LITER (PPB)) Version 2.0 Aug 1, 2001 PEAK MAX 4 DAY MAX 21 DAY MAX 60 DAY MAX 90 DAY GEEC AVG GEEC AVG GEEC AVG GEEC AVG GEEC RUN No. 5 FOR Paraquat dichlor ON Non select * INPUT VALUES * RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE NO-SPRAY INCORP ONE(MULT) INTERVAL Koc (PPM ) (%DRIFT) (FT) (IN) 0.534( 2.076) ******* GRHIFI( 6.6) FIELD AND STANDARD POND HALFLIFE VALUES (DAYS) METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED (FIELD) RAIN/RUNOFF (POND) (POND-EFF) (POND) (POND) N/A ****** GENERIC EECs (IN MICROGRAMS/LITER (PPB)) Version 2.0 Aug 1, 2001 PEAK MAX 4 DAY MAX 21 DAY MAX 60 DAY MAX 90 DAY GEEC AVG GEEC AVG GEEC AVG GEEC AVG GEEC

21 The maximum EEC, estimated by GENEEC2, for paraquat dichloride when used in Para-Ken mg/l (clover), mg/l (forestry), mg/l (Lucerne), mg/l (non-crop situations and non-selective weed control high rate) and mg/l (non-crop situations and non-selective weed control low rate). Calculation of acute risk quotients using GENEEC2 expected environmental concentrations Table 11 gives calculated acute risk quotients for each trophic level considering EEC estimated by GENEEC2 and lowest relevant toxicity figures The calculations are based on a conservative model taking into account the degradation of the substance and its adsorption potential in order to cover both run-off, drift input into water bodies. The model also considers information about the application method to determine how much of the substance will drift into water bodies. Table 11 risk quotients derived from the GENEEC2 model and toxicity data Species Peak EEC from GENEEC2 (mg/l) LC 50 or EC 50 (mg/l) Clover kg a.i./ha, 2 applications at 28 days interval RQ Trigger value / Presumption < 0.1 / Risk below concern Fish < 0.05 / Risk below concern for < 0.1 / Risk below concern Invertebrates < 0.05 / Risk below concern for Algae - Selenastrum capricornutum < 0.1 / Risk below concern < 0.05 / Risk below concern for Algae - diatom (Navicula pelliculosa) > 0.5 / High risk > 0.05 / High risk for threatened species Aquatic plant (Lemna gibba) < 0.1 / Risk below concern < 0.05 / Risk below concern for Forestry - 1 kg a.i./ha, 2 applications at 28 days interval Fish < 0.1 / Risk below concern Invertebrates (Daphnia magna) < 0.05 / Risk below concern for < 0.1 / Risk below concern < 0.05 / Risk below concern for

22 22 Species Peak EEC from GENEEC2 (mg/l) LC 50 or EC 50 (mg/l) RQ Trigger value / Presumption Algae - Selenastrum capricornutum Algae - diatom (Navicula pelliculosa) Aquatic plant (Lemna gibba) < 0.1 / Risk below concern < 0.05 / Risk below concern for > 0.5 / High risk > 0.05 / High risk for threatened species / Risk can be mitigated through restricted use > 0.05 / High risk for threatened species Lucerne kg a.i./ha, 2 applications at 28 days interval < 0.1 / Risk below concern Fish < 0.05 / Risk below concern for Invertebrates (Daphnia magna) < 0.1 / Risk below concern < 0.05 / Risk below concern for Algae - Selenastrum capricornutum < 0.1 / Risk below concern < 0.05 / Risk below concern for Algae - diatom (Navicula pelliculosa) > 0.5 / High risk > 0.05 / High risk for threatened species Aquatic plant (Lemna gibba) < 0.1 / Risk below concern > 0.05 / High risk for threatened species Barley grass control 1.5 kg a.i./ha, 4 applications at 28 days interval Fish < 0.1 / Risk below concern < 0.05 / Risk below concern for Invertebrates (Daphnia magna) < 0.1 / Risk below concern < 0.05 / Risk below concern for Algae - Selenastrum capricornutum < 0.1 / Risk below concern > 0.05 / High risk for threatened species

23 23 Species Peak EEC from GENEEC2 (mg/l) LC 50 or EC 50 (mg/l) RQ Trigger value / Presumption Algae - diatom (Navicula pelliculosa) Aquatic plant (Lemna gibba) > 0.5 / High risk > 0.05 / High risk for threatened species / Risk can be mitigated through restricted use > 0.05 / High risk for threatened species Barley grass control, lower rate 0.6 kg a.i./ha, 4 applications at 28 days interval Fish < 0.1 / Risk below concern < 0.05 / Risk below concern for Invertebrates (Daphnia magna) < 0.1 / Risk below concern < 0.05 / Risk below concern for Algae - Selenastrum capricornutum < 0.1 / Risk below concern < 0.05 / Risk below concern for Algae - diatom (Navicula pelliculosa) > 0.5 / High risk > 0.05 / High risk for threatened species Aquatic plant (Lemna gibba) / Risk can be mitigated through restricted use > 0.05 / High risk for threatened species Non-crop situations 1.5 kg a.i./ha, 4 applications at 28 days interval Fish < 0.1 / Risk below concern < 0.05 / Risk below concern for Invertebrates (Daphnia magna) Algae - Selenastrum capricornutum < 0.1 / Risk below concern < 0.05 / Risk below concern for < 0.1 / Risk below concern > 0.05 / High risk for threatened species Algae - diatom (Navicula pelliculosa) > 0.5 / High risk > 0.05 / High risk for threatened species

24 24 Species Peak EEC from GENEEC2 (mg/l) LC 50 or EC 50 (mg/l) RQ Trigger value / Presumption Aquatic plant (Lemna gibba) / Risk can be mitigated through restricted use > 0.05 / High risk for threatened species Conclusion for the aquatic acute risk assessment using GENEEC2 data The acute risks fish and aquatic invertebrates were below the level of concern for all the use scenarios High acute risks for algae were observed for all use scenarios. High acute risks for threatened plant species were observed for forestry, Lucerne, non-selective weed control and non-crop situations. Calculation of chronic risk quotients using GEENEC2 expected environmental concentrations Table 12 gives the calculated chronic risk quotients for each trophic level using the EEC estimated by GENEEC2 and lowest relevant toxicity figures. Table 12 Chronic risk quotients derived from the GENEEC2 model and toxicity data Species Relevant EEC from GENEEC2 (mg /L)* NOEC (mg/l) Clover seed kg a.i./ha, 4 applications at 28 days interval Chronic RQ Trigger value / Presumption < 1 / Risk below concern Invertebrates Daphnia magna (21 d) < 0.1 / Risk below concern for Non-crop situations: Fence lines, streets, industrial kg a.i./ha, 4 applications at 28 days interval Invertebrates Daphnia magna (21 d) < 1 / Risk below concern > 0.1 / High chronic risk to Forestry - 1 kg a.i./ha, 2 applications at 28 days interval Invertebrates Daphnia magna (21 d) < 1 / Risk below concern < 0.1 / Risk below concern for Lucerne kg a.i./ha, 2 applications at 28 days interval Invertebrates Daphnia magna (21 d) < 1 / Risk below concern < 0.1 / Risk below concern for

25 25 Species Relevant EEC from GENEEC2 (mg /L)* NOEC (mg/l) Chronic RQ Trigger value / Presumption Barley grass control kg a.i./ha, 4 applications at 28 days interval Invertebrates Daphnia magna (21 d) < 1 / Risk below concern > 0.1 / High chronic risk to Barley grass control, low rate kg a.i./ha, 4 applications at 28 days interval Invertebrates Daphnia magna (21 d) < 1 / Risk below concern < 0.1 / Risk below concern for * EEC selected must be as close as possible from the exposure duration of the study selected for risk assessment purpose. Conclusion for the aquatic chronic risk assessment using GENEEC2 data The chronic risks to aquatic invertebrates were below the level of concern; there were high chronic risks to threatened aquatic invertebrates species for non-crop situations and nonselective control at the highest application rate of 1.5 kg paraquat dichloride per hectare. There were no data to assess the chronic risks to fish. We consider that the lack of chronic data on fish does not prevent the conclusion of the risk assessment. AgDRIFT modelling The AgDRIFT tool was used to refine this result and provide an indication of the extent of the measures that would need to be taken to reduce the risks to organisms below the level of concern The AgDRIFT model does not give an EEC per se rather the model output is the buffer zone distance required to get a risk quotient < 1. Output from the AgDRIFT model The AgDRIFT tool uses buffer zones to mitigate the risks to non-target organisms, with higher risks resulting in larger buffer zone distances. As such, the buffer zone outputs of the model provide a relative measure of the risks to the environment and the extent of the mitigation measures that should be applied. The results of the AgDRIFT assessment confirmed that measures should be taken during use to ensure that waterways are not exposed to paraquat The model was run using the application rates and use patterns proposed for Para-Ken 250, which included coarse spray droplet sizes; the environmental fate characteristics for paraquat and the lowest acute figure for the most sensitive taxa (EC50 = mg/l) for paraquat dichloride (the diatom Navicula pelliculosa). The model results show that a buffer zone higher than 254 m (highest buffer zone possible to calculate in AgDRIFT) is needed for all use scenarios. It should be pointed out that a buffer zone greater than 254 m is applicable at 400 g a.i./ha, the lowest proposed application rate for Para-Ken 250. Due to the limitations of the model, it was not possible to provide a quantitative estimate of exposure with known

26 26 uncertainty, beyond the range of AgDRIFT. The additional safety factor for was not taken into consideration because there is currently no list of endangered algal species for NZ In conclusion, we consider that there are no adequate mitigation measures to protect algae from the application of Para-Ken 250. Groundwater risk assessment Estimated concentrations of chemicals with Koc values greater than 9995 L/kg are beyond the scope of the regression data used in the SCI-GROW model. We consider that due to the high adsorption of paraquat dichloride and the fact that it is almost immobile in the soil that it will not pose a potential risk of groundwater contamination. Sediment risk assessment Sediments may act as both a sink for chemicals through sorption of contaminants to particulate matter, and a source of chemicals through resuspension. Sediments integrate the effects of surface water contamination over time and space, and may thus present a hazard to aquatic communities (both pelagic and benthic) which is not directly predictable from concentrations in the water column When results from whole-sediment tests with benthic organisms are available the PNECsed has to be derived from these tests using assessment factors. However, the available sediment tests should be carefully evaluated. Special attention should be given to the pathways through which the test organisms are exposed to the chemical and the test protocol should carefully be checked to determine whether feeding with unspiked food has possibly reduced exposure via sediment ingestion. For assessing the toxicity of spiked sediment it is necessary to address adequately all possible routes of exposure. Sediment organisms can be exposed via their body surfaces to substances in solution in the overlying water and in the pore water and to bound substances by direct contact or via ingestion of contaminated sediment particles. The route that is most important is strongly influenced by species-specific feeding mechanisms and the behaviour of the organism in, or on, the sediment. Test design parameters can have a bearing on the route of uptake of a substance The PNECsed is derived from the lowest available NOEC/EC10 obtained in long-term tests by application of the following assessment factors and is then expressed as mg/kg of dry sediment: Table 13 Assessment factors for derivation of PNECsed Available test result One long-term test (NOEC or EC10) 100 Two long-term tests (NOEC or EC10) with species representing different living and feeding conditions 50

27 27 Available test result Three long-term tests (NOEC or EC10) with species representing different living and feeding conditions Using the toxicity figures from the tests with spiked sediment on the reproduction of Chironomus, and dividing by the appropriate assessment factor of 100, the calculated PNECsed is 1 mg/kg dry sediment for paraquat dichloride PEClocal for sediment can be compared to the PNEC for sediment dwelling organisms. The concentration in freshly deposited sediment is taken as the PEC for sediment, therefore, the properties of suspended matter are used. The concentration in bulk sediment can be derived from the corresponding water body concentration, assuming a thermodynamic partitioning equilibrium (see also Di Toro et al., 1991): PEClocal sed = K susp water RHO susp PEC local water 1000 Where PEClocal water concentration in surface water during release episode based on GENEEC2 modelling (mg/l) Ksusp-water suspended matter-water partitioning coefficient = 5.65 (m 3 /m 3 ). Equation R.16-7 of REACH TGD R16. RHOsusp bulk density of suspended matter = 1150 (kg/m 3 ) Equation R of REACH TGD R16. PEClocal sed predicted environmental concentration in sediment (mg/kg) The worst-case scenario for the concentration expected to be measured in pore-water is the expected concentration in the water column (i.e mg/l, according to GENEEC2), therefore PEClocal sed = mg/kg sediment for paraquat. The risk for sediment-dwelling organisms was assessed as the ratio PECsed/PNECsed. This ratio is for paraquat. Conclusion for the sediment risk assessment: Risks for sediment dwelling organisms due to paraquat are below the level of concern (LOC < 1). Terrestrial risk assessment For terrestrial organisms, toxicity-exposure ratios (TERs) are used for earthworms and birds, hazard quotients (HQ) were used for terrestrial invertebrates and RQs for bees. This convention results in concern arising if a risk quotient is less than the trigger value for earthworms and more than the trigger value for terrestrial invertebrates. We have adopted the

28 28 LOC developed by the European Union allowing us to determine whether a substance poses an environmental risk are provided in the Table 1. Table 14 Levels of concern as adopted by the EPA LOC Presumption Earthworm/ Birds TER < 10 High risk Chronic TER < 5 High risk Threatened bird species TER < 20 High risk Chronic TER < 10 High risk Threatened soil organisms species TER < 100 High risk Chronic TER < 50 High risk Bees RQoral/contact > 0.4 High risk Chronic RQ > 1 High risk Terrestrial invertebrates HQ in-field/off-field 2 High risk For more details about the different factors used for calculating TER and RQ refer to the relevant reference documents listed in Table 9. Earthworm risk assessment Soil Predicted Environmental Concentration (PEC) determination Both acute and reproductive earthworm tests are static tests where the test substance is applied to the system only once at the beginning of the test. Therefore, the nominal dose levels in the test match the initial concentrations in the field and thus it is appropriate to use initial PEC values (not time-weighted averages) for the acute as well as the long-term TER The concentration of active substance in the soil is calculated on the basis of the FOCUS (1997) document Soil persistence models and EU registration. PEC one application (mg/kg soil) = application rate (kg a.i./ha) kg soil Soil concentrations of the active ingredient are calculated by assuming the deposition would mix into the top 5 cm of soil, and this soil would have a bulk density of 1,500 kg/m 3, i.e. the deposition expressed in mg/m 2 would mix into 75 kg of soil In case of multiple applications, the following formula has to be used: